Can a Pill a Day ... Keep HIV Away?

What would it mean for the
future of the epidemic if
HIV-negative people could
take a pill to prevent HIV
infection? That may soon become a reality:
on May 10th, an FDA advisory panel
voted 19 to 3 to recommend approval of
the HIV medication Truvada as a prevention
tool for men who have sex with men.
The panel also voted 19 to 2 to recommend
it for any HIV-negative person who is in a
relationship with a partner who has HIV.

The FDA usually follows its committees'
recommendations, but is not required
to do so. It initially said it would announce
its decision on approval before June 15,
but later extended the target date until
September 14. The agency wants more time
to look at the proposed medication guide,
educational training, and the implementation
system for the possible rollout of PrEP
(pre-exposure prophylaxis). AIDS organizations
nationwide are eager to hear the
decision, since approval could transform
the way we think about HIV prevention.
In addition to condoms, safer sex education,
and behavioral counseling, a new
medical tool may soon be available.

A New Use for HIV Meds

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HIV meds have long proved essential for
helping people with HIV better manage
the virus. The introduction of AZT in
1987 changed the course of the epidemic
by prolonging lives and challenging the
perception that AIDS was a death sentence.
At the dose used back then, however,
it was highly toxic and came with
taxing side effects. The true breakthrough
came in 1995 with the introduction
of combination HIV therapy, a new
approach to treatment that allowed HIV-positive
people to lead healthier lives.

Recent research has presented a new
use of HIV meds: the "treatment as prevention"
model. One study found that
people with HIV are 96% less likely to
transmit HIV to their negative partners
when they start taking HIV meds earlier.
But the use of HIV meds to prevent transmission
has largely been limited to HIV-positive
people up to this point.

So it comes as a major development
that the FDA is currently reviewing
an application for use of the HIV med
Truvada as a prevention tool. Several
studies have found that HIV meds taken
daily by HIV-negative people can reduce
their chances of infection. Some doctors
already prescribe HIV meds as prevention,
but since the FDA does not allow
drug companies to market HIV meds for prevention, these are known as "off-label"
uses and are not covered by most
insurance plans.

The Evidence

Over a million people live with HIV
in the U.S., and an estimated 50,000
are newly infected each year. Recent
studies focusing on HIV vaccines and
microbicides (gels to prevent transmission)
have produced disappointing
results, and marginalized communities
continue to bear the brunt of failed
prevention efforts. People who are
oppressed based on race, class, gender,
and sexual orientation are at increasingly
high risk for HIV, creating more
complex challenges for prevention
programs. Transmission rates among
MSM are a particular area of concern.
The CDC estimates that HIV infections
among MSM increased by 34%
between 2006 and 2009. They increased
48% among MSM of color during the
same period. Thus, there is a sense of
urgency among AIDS advocates that
we need new prevention strategies.

Several studies have shown that PrEP
is an effective prevention tool, including
the "iPrEx" study, which was completed in
November 2010 in Brazil, Ecuador, Peru,
South Africa, Thailand, and the U.S. In
this study, a total of 2,499 HIV-negative
MSM and transgender women who have
sex with men took either a daily Truvada
pill or a placebo (sugar pill).

Researchers found that those taking
Truvada were 44% less likely to become
infected with HIV than those taking
the placebo. Among participants who
reported having unprotected receptive
anal intercourse, which is higher
risk for HIV, Truvada reduced infections
by 58%.

PrEP could be most effective for
people who have less control over condom
use, such as sex workers or people
who have sex under the influence of
drugs and alcohol. Additionally, a married
woman who has difficulty advocating
for safer sex with her husband could
use PrEP to protect herself if she suspects
he has other partners. Researchers were
unable to detect Truvada in the blood of
the majority of study participants who
took Truvada and became HIV positive.

This means they might not have been
taking the drugs as directed. In fact,
adherence was surprisingly low. While
people claimed an average of 90% adherence,
blood tests indicated an adherence
rate closer to 50%. On one hand, this
opens the possibility that PrEP could be
even more effective than iPrEx showed.
On the other hand, adherence rates
present a serious hurdle. If people in a
closely monitored study have difficulty
taking a daily drug, how can people be
expected to take meds consistently in the
"real world"?

In July 2011, the University of
Washington released early results for
its Partners PrEP study, which provided
Truvada, Viread, or a placebo to 4,758
serodiscordant (one partner HIV positive,
the other not) couples in Kenya and
Uganda. HIV meds were found to protect
the HIV-negative partners in the study
from infection. Those taking Truvada
had 73% fewer infections, while those
taking Viread had 62% fewer infections.

Unlike the iPrEx study, Partners PrEP
had a remarkably high level of 95% adherence
to the pills, which might explain
the higher success rates. These findings
suggest that PrEP is safe and effective for
heterosexuals as well as MSM, and that
serodiscordant couples might be a realistic
target population for PrEP.

But these studies leave many questions
unanswered. Given the short-term
nature of PrEP studies, what long-term
side effects can arise for people taking
PrEP indefinitely? Could PrEP protect
injection drug users, who have not
been addressed in any of these studies?
What would adherence to PrEP look
like without regular monitoring and
behavioral counseling? How might
PrEP affect women who are pregnant
or using hormonal birth control? How
do social factors like race, income, culture,
education, and nationality affect
adherence rates? And how do we pay
for it?

The Cost

Some worry that PrEP would not be available
to those who truly need it due to high
price. There is no guarantee that Medicaid,
Medicare, and private insurers would cover
the cost of PrEP. Many people at risk for
HIV are in low-income groups, and U.S.
patent laws will block the availability of
cheaper generic versions of PrEP.

Truvada can cost over $38 a day,
while condoms cost under a dollar
each. In meetings with clinicians
and community advocates, Gilead has
stated that the company has no plans to
market Truvada for prevention. But if
that changes, Gilead could make huge
profits by marketing the drug not only
to people with HIV, but to anyone at
risk of being infected. PrEP might be
available only for the wealthy, and not
to those at highest risk of HIV infection.
This would do little to address the
social inequalities that make HIV prevention
so complicated. And it would
favor those who already have access
to quality treatment while snubbing
poorer people.

If funding is used to make PrEP more
widely available, we face a challenge of
how to use limited resources. Using the
recently revised U.S. treatment guidelines
that recommend HIV treatment for
everyone with HIV, there are over 25 million
people in the world who are in need of
HIV meds but who do not have access to
them. In the U.S. alone, over 3,500 people
sit on waiting lists for HIV meds through
the AIDS Drug Assistance Programs
(ADAP). Can we justify investing in
PrEP for HIV-negative people while the
same drugs are unavailable to so many
who need treatment? People with HIV in
poor countries usually take cheaper generic
versions of HIV meds, while people in
the U.S. must pay more. A cynical cost-benefit
analysis of Gilead's potential profits
might encourage it to market PrEP in
the U.S., rather than increase the accessibility
of HIV meds all over the world.

A new study from Stanford University
looked at the drug and health care costs of
prescribing Truvada to MSM. Giving the
drug to all MSM would cost $480 billion
over 20 years, but targeting only those with
five or more partners a year would bring that number down to $85 billion. Over the next
two decades, they estimated 490,000 new
infections in the U.S. if PrEP is not used. But
even if it is only 44% effective, 41,000 new
infections would be prevented if high-risk
MSM took the drug. They conclude: "PrEP
in the general MSM population could prevent
a substantial number of HIV infections,
but it is expensive. Use in high-risk
MSM compares favorably with other interventions
that are considered cost-effective
but could result in annual PrEP expenditures
of more than $4 billion."

"Even though it provides good value,
it is still very expensive," said Jessie
Juusola, lead author of the study. "In the
current health-care climate, PrEP's costs
may become prohibitive, especially given
the other competing priorities for HIV
resources, such as providing treatment for
infected individuals."

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